HCA–MCA (METHOD 2)

Summary

HCA-MCA (Method 2) performs a full High Consequence Area (HCA)-Moderate Consequence Area (MCA) analysis workflow from start to finish. HCA-MCA (Method 2) is implemented as a ModelBuilder model tool using the tools from the Prepare and Process toolsets in the Gas HCA Tool Python toolbox. It creates a Gas HCA Tool project geodatabase, imports required source data into the same, performs data conditioning and intermediate calculations, and calculates HCA ranges by method 2 (the Potential Impact Radius (PIR) method) per 49 CFR §192.903(2), and MCA ranges per 84 FR 52180.

Usage

HCA-MCA (Method 2) implements G2-IS’ best practices for HCA-MCA analysis by method 2. However, because it is implemented as a ModelBuilder model tool, you are free to make a copy of the tool and modify it to suit your own needs.

The following tools are used in HCA-MCA (Method 2). They are listed in their order of execution within the HCA-MCA (Method 2) tool; the heading for each section below is a hyperlink to the detailed help for the tool. Please note that while the tools HCA-MCA (Method 2) uses are listed in order in which they are executed, the HCA-MCA (Method 2) tool parameters are shown in association with the tools that expose them, not necessarily in the order in which HCA-MCA (Method 2) lists them:

1) Initialize Database

Initialize Database tool creates a project file geodatabase for the HCA-MCA analysis. It stores copies of your input data (to preserve all data used in the analysis), as well as intermediate results and final HCA-MCA unit outputs. The first and last parameters exposed by the HCA-MCA tool are from Initialize Database.

Project Name – Your HCA-MCA analysis project is internally identified in the Gas HCA Tool project geodatabase by a Global Unique Identifier (GUID) value. Your designated project name serves as an informal, human-readable name for your analysis project.
Output Project Geodatabase – Initialize Database creates a new file geodatabase to store the project data.

2) Copy Centerlines

Copy Centerlines copies your centerline features from your pipeline database into the CENTERLINE feature class in the project geodatabase. Although it’s not a requirement to preserve input data, doing so enables you to retain an archival copy of the input data used in the analysis.

Input Centerline Features – Your input centerline features should consist of the continuous, non-branching runs of pipeupon which you desire to perform calculations.

Your input centerline features must contain the following attributes (your field names need not match, but fields containing this information must be present):

- - Centerline Identifier Field – A field that uniquely identifies each input centerline feature. Your centerline ID field is preserved in the ORIGINAL_ROUTE_ID field in the CENTERLINE feature class in the project geodatabase.
  - Centerline Begin Measure Field – A field that defines the begin measure values of your centerline features.
  - Centerline End Measure Field – A field that defines the end measure values of your centerline features.

3) Prepare Structures

Prepare Structures copies your point and/or polygon Building Intended for Human Occupancy (BIHO) features from your pipeline database into your project geodatabase for use in the analysis. The output features are stored in the following feature classes in the project geodatabase: STRUCTURE_POINT and STRUCTURE_POLYGON.

Input Structures Features – This parameter allows you to select multiple input layers or feature classes, and to mix point and polygon shape types in the input feature layers or feature classes. However, all input layers/feature classes must have a common schema. Your input BIHO features must contain the following attributes (your field names need not match, but fields containing this information must be present):
- - Structure Identifier Field – A field that uniquely identifies each input BIHO feature. Your structure ID field is preserved in the ORIGINAL_STR_OR_AREA_ID field in the STRUCTURE_POINT and STRUCTURE_POLYGONfeature classes in the project geodatabase.
  - Number of Dwelling Units Field – This parameter indicates the number of dwelling units present in the BIHO feature. For a single-family residence, the number is 1. For an apartment structure, the number is the number of apartment units in the feature.
  - Number of Stories Field – This field contains the number of stories in the BIHO feature. This field is used in the determination of Class 4 ranges in Class Location analysis. This field is not used in HCA-MCA analysis.
  - Discovery Date Field for Structures – This optional field stores the date on which the BIHO feature was actually discovered in the field.
  - Database Date for Structures – This optional field stores the date on which the BIHO feature was entered into your pipeline database.

4) Prepare Qualifying Areas

Prepare Qualifying Areas tool copies your point or polygon features for identified sites from your pipeline database into your project geodatabase. The output features are stored in the following feature classes in the project geodatabase: QUALIFYING_AREA_POINT and QUALIFYING_AREA_POLYGON. (Note these feature classes are also used to store qualifying outside area and building features for Class Location, hence the names of the feature classes and their attributes.)

Input Identified Site Features – This parameter allows you to select multiple input layers or feature classes, and to mix point and polygon shape types in the input feature layers or feature classes. However, all input layers/feature classes must have a common schema. Your input identified site features must contain the following attributes (your field names need not match, but fields containing this information must be present):
- - Identified Site Identifier Field – A field that uniquely identifies each input identified site feature. Your identified site identifier field is preserved in the ORIGINAL_STR_OR_AREA_ID field in the QUALIFYING_AREA_POINT and QUALIFYING_AREA_POLYGON feature classes in the project geodatabase.
  - Identified Site Type Field – A field that defines the type of identified site. This field is intended primarily for use in map display; all features in the QUALIFYING_AREA_POINT and QUALIFYING_AREA_POLYGON feature classes are used in analysis.
  - Discovery Date Field for Identified Sites – This optional field stores the date on which the identified site feature was actually discovered in the field.
  - Database Date for Identified Sites – This optional field stores the date on which the identified site feature was entered into your pipeline database.

5) Prepare Pipe Segment and MAOP Features

Prepare Pipe Segment and MAOP Features copies your pipeline database pipe segment and Maximum Allowable Operating Pressure (MAOP) features (or records) to the PIPESEGMENT and MAOP tables, respectively in the project geodatabase.

Input Pipe Segment Features – Typically, your input pipe segment features/records correspond to discrete lengths of pipe with common attributes stored on your pipeline centerlines. Your input pipe segment features/records must contain the following attributes (your field names need not match, but fields containing this information must be present):
- - Pipe Segment Centerline Identifier Field – This field uniquely identifies the centerline feature on which the pipe segment feature/record occurs. This field will be mapped to and compared with ORIGNIAL_ROUTE_ID field in CENTERLINE layer.
  - Pipe Segment Begin Measure Field – A field that represents the begin measure of the pipe segment.
  - Pipe Segment End Measure Field – A field that represents the end measure of the pipe segment.
  - Pipe Segment Outside Diameter Field – A field that represents the diameter of the pipe segment in inches.
Input MAOP Features – Typically, your input MAOP features/records correspond to centerline segments with common MAOP values. Your input MAOP features/records must contain the following attributes (your field names need not match, but fields containing this information must be present):
- - MAOP Centerline Identifier Field – This field uniquely identifies the centerline feature on which the MAOP feature/record occurs. This field will be mapped to and compared with ORIGNIAL_ROUTE_ID field in CENTERLINE layer.
  - MAOP Begin Measure Field – A field that represents the begin measure of the MAOP segment.
  - MAOP End Measure Field – A field that represents the end measure of the MAOP segment.
  - MAOP Field – A field that the MAOP value (in PSI) of the segment.

6) Create Centerline PIR Buffers

Create Centerline PIR Buffers creates centerline PIR segments on your centerline features, and then creates centerline PIR segment buffer polygons. The output features are stored in the following feature classes in the project geodatabase: HCA_PIR_SEGMENT and HCA_PIR_SEGMENT_BUFFER.

PIR Factor – The PIR combustion factor varies based on product type. 0.69, the factor for ‘dry’ natural gas, is the default value. 0.73 is the factor for ‘wet’ natural gas.
Additional PIR Tolerance (Feet) – This parameter enables you to specify an additional tolerance (in Feet) to add to the PIR, to account for uncertainty in the spatial location of your centerline, BIHO and identified site features.

7) Create Structures and Site PIR Buffers

Create Structure and Site PIR Buffers creates PIR buffer polygons on your BIHO and identified site features and then generates centerline PIR BIHO and identified site segments by intersecting the buffer polygons for BIHOs and identified sites with your centerline features. The output features are stored in the following feature classes in the project geodatabase: HCA_STRUCTUREBUFFER and HCA_STRUCTURESEGMENT.

HCA-MCA (Method 2) exposes none of this tool’s parameters.

8) Prepare Roads

Prepare Roads copies your input road polyline features to the project geodatabase, then buffers the road features to the road width, buffers the road width polygons by the PIR, and finally intersects the road width PIR buffers with the pipeline centerlines to create road PIR centerline segments. The output features are stored in the following feature classes in the project geodatabase: SOURCE_ROADS, ROAD_WIDTH_BUFFER, ROAD_WIDTH_PIR_BUFFER, and ROAD_PIR_SEGMENTS.

Input Road Features – Road data sources and schemas vary widely. The tool assumes that you have already created an appropriate roads feature class or feature layer containing only designated interstates, other freeways, or expressways, as well as any other principal arterial roadways with 4 or more lanes, as defined in the Federal Highway Administration’s Highway Functional Classification Concepts, Criteria and Procedures, Section 3.1. Your road features must contain the following attributes:
- - Road Width Fields – Your input road features must contain one or more fields that, when combined, define the paved surface width, including shoulders, of your road features. The field(s) you select are summed to arrive at total road paved surface width.
  - Roads Width Unit Field – This parameter allows you to specify the linear units for your road width attributes. Units can be either ‘Feet’ or ‘Meters.’
  - Road Width Divisible Factor Field – Your road width attributes likely defines the actual road width. When buffering the road polyline features to create road polygons, a value of half the road width is generally used, since the buffer operation buffers both sides of your road features. This parameter defines the value by which the sum of your road attributes is divided to arrive at a proper buffer radius width. The default value is 2 and need not be modified in most instances.
  - Road Width Tolerance Field – This parameter allows you to specify an additional road width spatial tolerance to be added to be to the road width buffer distance to account for uncertainty in the spatial position of your road and/or centerline features.

9) HCA-MCA Calculation (Method 2)

HCA-MCA Calculation (Method 2) performs the final step in the HCA-MCA analysis workflow, determining HCA and MCA ranges by method 2. This tool also produces dynamically segmented HCA and MCA segments that retain much useful attributes from the analysis process. The output features are stored in the following feature classes in the project geodatabase: HCA_RANGE_M2, HCA_SEGMENT_COUNT_M2.

Boundary Adjustment Method – Arc Method (also called radial arc method) – This parameter calculates HCA-MCA extensions; the non-extended HCA-MCA range ends where the terminal BIHO or identified site buffer of the HCA-MCA range intersects the pipeline centerline; it is then extended by the length of the PIR, executed as the point at which a PIR buffer centered on the end of the non-extended HCA-MCA range intersects the centerline, as illustrated in 49 CFR §192 Appendix E.(I.) Figure A. The arc method is strongly recommended.

Syntax

HCAMCAMethod2 (Project_Name, Input_Centerline_Features, Centerline_Identifier_Field, Centerline_Begin_Measure_Field, Centerline_End_Measure_Field, Input_Structure_Features, Structure_Identifier_Field, Number_of_Dwelling_Units_Field, Number_of_Stories_Field, {Database_Date_Field_for_Structures}, {Discover_Date_Field_for_Structures}, Input_Identified_Site_Features, Identified_Site_Identifier_Field, {Database_Date_for_Identified_Sites}, {Discovery_Date_Field_for_Identified_Sites}, Input_Pipe_Segment_Features, Pipe_Segment_Centerline_Identifier_Field, Pipe_Segment_Begin_Measure_Field, Pipe_Segment_End_Measure_Field, Pipe_Segment_Outside_Diameter_Field, Input_MAOP_Features, MAOP_Centerline_Identifier_Field, MAOP_Begin_Measure_Field, MAOP_End_Measure_Field, MAOP_Field, PIR_Factor, {Additional_Tolerance_for_PIR__Feet_}, Input_Road_Features, Road_Width_Field, Roads_Width_Unit_Field, Roads_Width_Divisible_Factor_Field, Roads_Width_Tolerance_Field, Boundary_Adjustment_Method, Output_Project_Geodatabase)

Parameter	Explanation	Data Type
Project_Name	Dialog Reference Specify your project name. There is no Python reference for this parameter.	String
Input_Centerline_Features	Dialog Reference Specify your input centerline features. There is no Python reference for this parameter.	Table View
Centerline_Identifier_Field	Dialog Reference Select the field that uniquely identifies your input centerline features. There is no Python reference for this parameter.	Field
Centerline_Begin_Measure_Field	Dialog Reference Specify the field that contains the begin measure values for your input centerline features. There is no Python reference for this parameter.	Field
Centerline_End_Measure_Field	Dialog Reference Specify the field that contains the end measure values for your input centerline features. There is no Python reference for this parameter.	Field
Input_Structures_Features	Dialog Reference Specify your input BIHO features. You may select multiple point and polygon feature layers or feature classes. There is no Python reference for this parameter.	Multiple Value
Structure_Identifier_Field	Dialog Reference Specify the field that uniquely identifies each BIHO feature. There is no Python reference for this parameter.	String
Number_of_Dwelling_Units_Field	Dialog Reference Specify the field that defines the number of dwelling units in each BIHO feature. There is no Python reference for this parameter.	String
Number_of_Stories_Field	Dialog Reference Specify the field that defines the number of stories in each BIHO feature. There is no Python reference for this parameter.	String
Database_Date_Field_for_Structures (Optional)	Dialog Reference Specify the field that records the date at which your BIHO features were added to your pipeline database. There is no Python reference for this parameter.	String
Discover_Date_Field_for_Structures (Optional)	Dialog Reference Specify the field that records the ‘discovery date’ of your BIHO features. There is no Python reference for this parameter.	String
Input_Identified_Site_Features	Dialog Reference Specify your input identified site features. You may select multiple point and polygon feature layers or feature classes. There is no Python reference for this parameter.	Multiple Value
Identified_Site_Identifier_Field	Dialog Reference Specify the field that uniquely identifies your identified sites. There is no Python reference for this parameter.	String
Identified_Site_Type_Field	Dialog Reference Specify the field that defines identified site type. There is no Python reference for this parameter.	String
Database_Date_for_Identified_Sites (Optional)	Dialog Reference Specify the field that records the date at which your identified site features were added to your pipeline database. There is no Python reference for this parameter.	String
Discovery_Date_Field_for_Identified_Sites (Optional)	Dialog Reference Specify the field that records the ‘discovery date’ of your identified site features. There is no Python reference for this parameter.	String
Input_Pipe_Segment_Features	Dialog Reference Specify your input pipe segment features/records. There is no Python reference for this parameter.	Table View
Pipe_Segment_Centerline_Identifier_Field	Dialog Reference Specify the field that uniquely identifies the centerline segment on which the pipe segment feature/record occurs. There is no Python reference for this parameter.	Field
Pipe_Segment_Begin_Measure_Field	Dialog Reference Specify the field containing the begin measure value of the pipe segment feature/record on the underlying centerline feature. There is no Python reference for this parameter.	Field
Pipe_Segment_End_Measure_Field	Dialog Reference Specify the field containing the end measure value of the pipe segment feature/record on the underlying centerline feature. There is no Python reference for this parameter.	Field
Pipe_Segment_Outside_Diameter_Field	Dialog Reference Specify the field that stores the outside diameter (in inches) of the pipe segment feature/record. There is no Python reference for this parameter.	Field
Input_MAOP_Features	Dialog Reference Specify your input MAOP features/records. There is no Python reference for this parameter.	Table View
MAOP_Centerline_Identifier_Field	Dialog Reference Specify the field that uniquely identifies the centerline segment on which the MAOP feature/record occurs. There is no Python reference for this parameter.	Field
MAOP_Begin_Measure_Field	Dialog Reference Specify the field containing the begin measure value of the MAOP feature/record on the underlying centerline feature. There is no Python reference for this parameter.	Field
MAOP_End_Measure_Field	Dialog Reference Specify the field containing the end measure value of the MAOP feature/record on the underlying centerline feature. There is no Python reference for this parameter.	Field
MAOP_Field	Dialog Reference Specify the field that stores the MAOP value (in PSI) of the MAOP feature/record. There is no Python reference for this parameter.	Field
PIR_Factor	Dialog Reference Enter the PIR combustion factor for the PIR calculation. 0.69, the factor for ‘dry’ natural gas, is the default value. There is no Python reference for this parameter.	Double
Additional_Tolerance_for_PIR__Feet_ (Optional)	Dialog Reference Enter an additional tolerance (in Feet) to add to the PIR, if desired. The default value is 0 feet. There is no Python reference for this parameter.	Double
Input_Road_Features	Dialog Reference Specify your input road features. There is no Python reference for this parameter.	Feature Layer
Road_Width_Field	Dialog Reference Select your input road width field(s). There is no Python reference for this parameter.	Multiple Value
Roads_Width_Units_Field	Dialog Reference Select the desired road width linear units of measure. The default is ‘Feet’. There is no Python reference for this parameter.	String
Roads_Width_Divisible_Factor_Field	Dialog Reference Specify the value by which to divide the sum of the road width field values. The default value is 2. There is no Python reference for this parameter.	Long
Roads_Width_Tolerance_Field (Optional)	Dialog Reference Specify an additional road width tolerance value, if desired. There is no Python reference for this parameter.	Double
Boundary_Adjustment_Method	Dialog Reference Specify the method used to determine the spatial extent of clustered HCA-MCA ranges. There is no Python reference for this parameter.	String
Output_Project_Database	Dialog Reference Specify the destination of your output project geodatabase. There is no Python reference for this parameter.	Workspace

Code sample

The following script demonstrates how to use the HCA-MCA (Method 2) master tool with file geodatabase data.

# Import GasHCA Library

import hcapy

# improt Gas HCA Tools

arcpy.ImportToolbox(“C:\Python27\ArcGIS10.6\Lib\site-packages\hcapy\esri\Toolboxes\GasHCA Master Tools (Desktop)

.tbx”)

Project_Name = “HCAMCAMethod2”

Input_Centerline_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\StationSeries”

Centerline_Identifier_Field = “EVENTID”

Centerline_Begin_Measure_Field = “BEGIN_MEASURE”

Centerline_End_Measure_Field = “END_MEASURE”

Input_Structure_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\Structure_BIHO”

Structure_Identifier_Field = “EVENTID”

Number_of_Dwelling_Units_Field = “Num_Units”

Number_of_Stories_Field = “Num_Stories

Structure_Buffer_Distance = 660

Discovery_Date_Field_for_Structures = None

Database_Date_Field_for_Structures = None

Input_Identified_Site_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\Identified_Site”

Identified_Site_Identifier_Field = “StructorSiteID”

Identified_Site_Type_Field = “Identified_Site_Type”

Database_Date_for_Identified_Sites = None

Discovery_Date_Field_for_Identified_Sites = None

Input_Pipe_Segment_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\PipeSegment”

Pipe_Segment_Centerline_Identifier_Field = “RouteEventID”

Pipe_Segment_Begin_Measure_Field = “BEGIN_MEASURE”

Pipe_Segment_End_Measure_Field = “END_MEASURE”

Pipe_Segment_Outside_Diameter_Field = “Outsidediameter”

Input_MAOP_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\MAOP”

MAOP_Centerline_Identifier_Field = “RouteEventID”

MAOP_Begin_Measure_Field = “BEGIN_MEASURE”

MAOP_End_Measure_Field = “END_MEASURE”

MAOP_Field = “ActualPressure”

PIR_Factor = 0.69

Additional_PIR_Tolerance__Feet_ = 0

Input_Road_Features = r”C:\projects\GasHCA_Enhancements\Test.gdb\Tx_Roads”

Road_Width_Fields = “RB_WID;MED_WID”

Roads_Width_Unit = “Feet”

Roads_Width_Divisible_Factor = 2

Roads_Width_Tolerance = 0

Boundary_Adjustment_Method = “Arc Method”

Output_Project_Geodatabase = r”C:\projects\GasHCA_Enhancements\A_DOTCLass_Test5.gdb”

# Execute Tool

HCAMCAMethod2 (Project_Name, Input_Centerline_Features, Centerline_Identifier_Field, Centerline_Begin_Measure_Field, Centerline_End_Measure_Field, Input_Structures_Features, Structure_Identifier_Field, Number_of_Dwelling_Units_Field, Number_of_Stories_Field, Database_Date_Field_for_Structures, Discover_Date_Field_for_Structures, Input_Identified_Site_Features, Identified_Site_Identifier_Field, Identified_Site_Type_Field, Database_Date_for_Identified_Sites, Discovery_Date_Field_for_Identified_Sites, Input_Pipe_Segment_Features, Pipe_Segment_Centerline_Identifier_Field, Pipe_Segment_Begin_Measure_Field, Pipe_Segment_End_Measure_Field, Pipe_Segment_Outside_Diameter_Field, Input_MAOP_Features, MAOP_Centerline_Identifier_Field, MAOP_Begin_Measure_Field, MAOP_End_Measure_Field, MAOP_Field, PIR_Factor, Additional_PIR_Tolerance__Feet_, Input_Road_Features, Road_Width_Fields, Roads_Width_Unit, Roads_Width_Divisible_Factor, Roads_Width_Tolerance, Boundary_Adjustment_Method, Output_Project_Geodatabase)

Environments

Current Workspace, Scratch Workspace, Default Output Z Value, M Resolution, M Tolerance, Output M Domain, Output XY Domain, Output Z Domain, Output Coordinate System, Extent, Geographic Transformations, Output has M values, Output has Z values, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance

Licensing information

This tool requires a valid Gas HCA Tool user license or subscription. Please see the Request License and Register License tool help topics for details on obtaining and registering a Gas HCA Tool software license.

Credits

Use limitations

There are no access and use limitations for this item.